Officially the referendum is only on whether or not to accept the proposed bailout. However, the leaders of many of the other Eurozone members have said that Greece will be able to keep the Euro if and only if it votes yes, so there's a good chance Greece will have to leave the Euro immediately after a no vote. The Greek government has claimed that they will have a new deal within 48 hours of a no vote, but it's not entirely clear how they can achieve this.
Officially the referendum is only on whether or not to accept the proposed bailout. However, the leaders of many of the other Eurozone members have said that Greece will be able to keep the Euro if and only if it votes yes, so there's a good chance Greece will have to leave the Euro immediately after a no vote. The Greek government has claimed that they will have a new deal within 48 hours of a no vote, but it's not entirely clear how they can achieve this.